Processed foods are produced by using various methods, used widely, and essential for recent eating habit. Their taste, form, and properties easily change depending on their processings, and may be often deteriorated depending on their preserving conditions. As a technique to process food materials, raw food materials such as raw vegetables have been processed through a step of blanching by soaking in a large amount of heated aqueous solution. The main object of blanching is to inactivate enzymes contained in food materials by heating to prevent them from their quality change and deterioration by their own enzymatic reactions, to extend the range of seasoning choice, and to remove harshness and macerate tissues for facilitating the production of various processed foods. However, it has been known that the inherent color of food materials is lost by changing the quality in a heated aqueous solution and that the preservative stability of the obtained products is deteriorated. As a method to improve them, those which freeze processed foods and enclose them by using inactivated gases have been proposed. As a method to improve them with saccharides, for example, Japanese Patent Kokai No.270,765/00 discloses a method to soak processed foods in a cyclodextrin solution after blanching where green and yellow vegetables processed by the method less fade during storing. However, these methods have the drawback that is difficult to apply to food materials which are easily changed in quality and deteriorated by blanching.